Since the advent of electricity, technological developments have been continuously sought to harness natural resources for the production of electrical power. National economies and in many ways the entire global financial system now increasingly depend on the availability of abundant and low cost energy to fuel growth and maintain stability. Fossil fuels have long been a dominant source for the production of electrical power due to the relative abundance of fossil fuel resources and the low cost of such resources per unit of power produced. However, given the rapid growth of economies in developing nations and the ever increasing power demands of already developed nations, the demand for fossil fuels can often put pressure on the ability of suppliers to meet those demands. Furthermore, the concentration of certain resources in specific geographical regions that lack stability can create concerns regarding energy security. Thus, for example, there is a push within the United States to increase energy security by decreasing dependence on foreign energy production resources.
The prospect of climate change has also caused increasing pressure to reduce the dominance of fossil fuels, the burning of which releases green house gases that may contribute to global warming. Accordingly, alternative and often “green” sources of electrical power have been sought in recent years. Wind power and solar power projects are expanding rapidly to augment hydroelectric power production facilities that have been in service in relation to dams that have been built over the years. However, dams are not the only way to harness the power of water and convert such power into electrical energy. For example, some devices have been developed to harness the power of tides and waves. In relation to tide and wave based power production methods, as with other power production mechanisms, efficiency is often a concern.
Some examples of devices that may be used to harness wave power include an attenuator, point absorber, oscillating wave surge converter, an oscillating water column, an overtopping device and a submerged pressure differential device. The attenuator is typically a floating device that “rides” waves as they pass. The point absorber is also a floating device that absorbs wave energy while bobbing. However, both the attenuator and the point absorber utilize the mainly linear up and down motion of bobbing or wave riding as the mechanism for energy extraction and this ends up being inefficient as the motion of the particles in the wave itself is trochoidal. The oscillating wave surge converter has a tethered arm that moves in response to wave surges, while the submerged pressure differential device response to the pressure differential created by waves is to pump a fluid used to generate electricity. The oscillating water column device and the overtopping device use water turbines to create energy. Thus, none of the above listed wave energy extraction mechanisms may be able to take full advantage of the trochoidal nature of wave particle motion to improve energy efficiency.
Accordingly, it may be desirable to develop an improved wave energy extraction device.